Of the more than 2700 species of snakes, a few are IR-sensitive, that is, they have evolved specialized receptors by which they can detect and respond to electromagnetic radiation in the IR range.
All IR-sensitive snakes pose dangers to humans. At least eighteen species are venomous. The venomous IR-sensitive snakes are collectively known as the "pit vipers" and are divided among three genera of the family Viperidae: Agkistrodon, Crotalus, and Sistrurus. Copperheads and cottonmouths comprise the genus Agkistrodon, while the rattlesnakes comprise the genera Crotalus and Sistrurus.
All pit vipers are distinguished by an indentation, or "pit"--one below each eye--which contains numerous receptors that detect IR radiation. Pit vipers are also distinguished by their propensity for attacking suddenly and by their ability to deliver venoms comprised of mixtures of various hemotoxins and/or neurotoxins.
Pit vipers are distributed throughout much of North America, Central America, and South America; they account for virtually all venomous snake bites in the United States. About 1000 rattlesnake bites occur each year in the United States; about 3% are fatal. The Western Diamondback rattlesnake (Crotalus atrox) is responsible for the greatest number of fatal snake bites in the United States. The numbers of attacks and the numbers of fatalities are increasing each year.
A second snake family, Boidae, includes the remaining known IR-sensitive species: boa constrictors, pythons, and anacondas. These snakes are found in sub-tropical areas of the world, and they all have IR-sensitive receptors lining their upper and lower lips. Generally docile, these snakes attain enormous size, and while they are not venomous, they do occasionally attack and kill humans, as well as pets and domestic animals. They are, not unreasonably, considered a menace in those parts of the world where they are common.
Although most rational humans try to avoid contact with pit vipers and boids, the habitats of these snakes are becoming increasingly susceptible to human encroachment. Furthermore, in many areas, such as national forests and parks, pit viper and boid populations are increasing as a result of government protection statutes and programs. Consequently, in some areas there is a reasonable likelihood of untoward interactions occurring between IR-sensitive snakes and humans. Coming upon these snakes unexpectedly can be a frightening experience and people often react reflexively to beat or stomp the snake. Such responses can enrage and/or injure the animal unnecessarily and often lead to the human being bitten.
At present, a safe, reliable and convenient means of repelling pit vipers and boids without risk of injury to the person and/or the snake is not available. Those who frequent areas in which pit vipers and boids are prevalent would benefit from an easily portable device with which one can repel IR-sensitive snakes without coming into close proximity with the snakes. Likewise, property owners would benefit from a device with which they can exclude dangerous pit vipers or boids from their property without excluding harmless snakes, which control vermin.